Epilepsy afflicts approximately 1% of the population, yet close to 30% of this population proves drug resistant, leaving surgical resection as the last treatment option (Hauser and Hesdoffer, 1990). Recently, Haberman et al. (2003) established a novel gene therapy platform where neuroactive peptides are expressed and constitutively secreted. These AAV vectors expressed and secreted enough galanin in vivo to significantly attenuate both focal and generalized limbic seizure activity. Furthermore, McCown (2006) recently showed that AAV vectors that expressed and secreted galanin could significantly attenuate, or even block, limbic seizure activity. However, two important issues must be addressed prior to any clinical consideration. In humans, any gene therapy will inevitably encounter both seizure-induced pathological tissue and pre-existing immunity to AAV serotype 2. The present proposal will first determine the most efficacious AAV vector configuration in a model of chronic seizure activity, focusing upon AAV serotype 5, self-complementary AAV and a human synapsin promoter. Secondly, as found by Peden et al. (2004), studies will confirm the ability of AAV serotype 5 vectors to evade immunity to AAV serotype 2 with a particular focus on anti-seizure efficacy. To further optimize the anti-seizure efficacy, studies will determine if the inclusion of a furin cleavage site supports the expression and secretion of two or more gene products from a single AAV vector, thus increasing the potential therapeutic applications of AAV vectors to CNS disorders. All together, these studies will provide information crucial for devising the most effective AAV vector antiepileptic gene therapy, as well as establish novel technological advances that will greatly benefit the entire gene therapy community. Epilepsy afflicts approximately 1% of the population, yet close to 30% of this population prove drug resistant, leaving surgical resection as the last treatment option. The present proposed studies will define the most efficacious adeno-associated virus vector which will provide a viable gene therapy treatment for intractable epilepsy.